package com.example.demo;

public class Test {

    public static void main(String[] args) {
//        Integer a = null;
//        Integer b = null;
//        System.out.println(new StringBuilder().append(a).append(b).toString());
        String s = "aaaa_bbbbb_ccc_%s";
        String format = String.format(s, 11);
        System.out.println(format);
    }
}
